Classification of pseudohypoaldosteronism type II as type IV renal tubular acidosis: results of a literature review.

Pseudohypoaldosteronism (PHA) type II (PHA2) is a genetic disorder that leads to volume overload and hyperkalemic metabolic acidosis. PHA2 and PHA type I (PHA1) have been considered to be genetic and pediatric counterparts to type IV renal tubular acidosis (RTA). Type IV RTA is frequently found in adults with chronic kidney disease and is characterized by hyperchloremic hyperkalemic acidosis with normal anion gap (AG). However, we recently observed that PHA1 was not always identical to type IV RTA. In this study, we focused on the acid-base balance in PHA2. Through a literature search published between 2008-2020, 46 molecularly diagnosed cases with PHA2 were identified (median age of 14 years). They comprised 11 sets of familial and 16 sporadic cases and the pathology was associated with mutations in WNK 4 (n = 1), KLHL3 (n = 17), and CUL3 (n = 9). The mean potassium (K+) level was 6.2 ± 0.9 mEq/L (n = 46, range 4.0-8.6 mEq/L), whereas that of chloride (Cl-) was 110 ± 3.5 mEq/L (n = 41, 100-119 mEq/L), with 28 of 41 cases identified as hyperchloremic. More than half of the cases (18/35) presented with metabolic acidosis. Although AG data was obtained only in 16 cases, all but one cases were within normal AG range. Both Cl- and HCO3- levels showed significant correlations with K+ levels, which suggested that the degree of hyperchloremia and acidosis reflect the clinical severity, and is closely related to the fundamental pathophysiology of PHA2. In conclusion, our study confirmed that PHA2 is compatible with type IV RTA based on laboratory findings.

TRANSIENT PSEUDOHYPOALDOSTERONISM SECONDARY TO URINARY TRACT INFECTION IN A MALE INFANT WITH UNILATERAL HYDRONEPHROSIS DUE TO PRIMARY OBSTRUCTIVE MEGAURETER: A CASE REPORT.

We present a case of transient form of type 1 pseudohypoaldosteronism (S-PHA) in a 1.5-month-old male infant who presented with lethargy, failure to thrive, severe hyponatremia (Na=118 mmol/L), hypochloremia (Cl=93 mmol/L) and fever due to urinary tract infection. Potassium levels were normal. Markedly elevated serum aldosterone level and elevated serum renin confirmed the diagnosis of pseudohypoaldosteronism. Renal ultrasound showed grade III hydronephrosis on the left kidney while contrast-enhanced voiding urosonography excluded the existence of vesicoureteral reflux, which raised suspicion of obstructive uropathy at the level of vesicoureteral junction. Serum sodium normalized after several days of intravenous fluids and antibiotic therapy, after which oral supplementation of sodium was introduced. The levels of 17-hydroxyprogesterone, adrenocorticotropic hormone, cortisol and thyroid-stimulating hormone were normal. Functional magnetic resonance urography conducted at the age of 3 months confirmed the diagnosis of primary congenital obstructive megaureter and the infant was referred to a pediatric surgeon. Although a rare occurrence, S-PHA can be a potentially life-threatening condition in infants if not recognized and treated appropriately. Therefore, serum concentrations of electrolytes should be obtained in every child diagnosed with obstructive anomaly of the urinary tract and/or acute cystopyelonephritis. On the other hand, every child diagnosed with S-PHA should be evaluated for obstructive anomaly of the urinary tract.

A case report of pseudohypoaldosteronism type II with a homozygous KLHL3 variant accompanied by hyperthyroidism.

BACKGROUND: Pseudohypoaldosteronism type II (PHAII), also called Gordon syndrome, is a rare hereditary disease caused by variants in the WNK1, WNK4, KLHL3 and CUL3 genes. The combination of PHAII with hyperthyroidism and secondary hyperparathyroidism has not been reported previously. CASE PRESENTATION: A 54-year-old female with recently diagnosed Graves' disease presented hyperkalemia, hypertension, hypercalciuria, elevated levels of parathyroid hormone (PTH) and normal renal function. PHAII was established based on the finding of a homozygous variant (c.328 A > G, T110A) in the KLHL3 gene. Low-dose thiazide diuretics normalized her potassium, calcium and PTH. CONCLUSIONS: PHAII caused by a KLHL3 variant can affect adults later in life. This diagnosis should be considered in patients with hypertension, consistent hyperkalemia, and normal eGFR and can be corrected by thiazides. The patient also had hyperthyroidism and secondary hyperparathyroidism. The latter was also corrected by thiazide treatment. The hyperthyroidism was assumed to be unrelated to PHAII.

A mouse model of pseudohypoaldosteronism type II reveals a novel mechanism of renal tubular acidosis.

Pseudohypoaldosteronism type II (PHAII) is a genetic disease characterized by association of hyperkalemia, hyperchloremic metabolic acidosis, hypertension, low renin, and high sensitivity to thiazide diuretics. It is caused by mutations in the WNK1, WNK4, KLHL3 or CUL3 gene. There is strong evidence that excessive sodium chloride reabsorption by the sodium chloride cotransporter NCC in the distal convoluted tubule is involved. WNK4 is expressed not only in distal convoluted tubule cells but also in ß-intercalated cells of the cortical collecting duct. These latter cells exchange intracellular bicarbonate for external chloride through pendrin, and therefore, account for renal base excretion. However, these cells can also mediate thiazide-sensitive sodium chloride absorption when the pendrin-dependent apical chloride influx is coupled to apical sodium influx by the sodium-driven chloride/bicarbonate exchanger. Here we determine whether this system is involved in the pathogenesis of PHAII. Renal pendrin activity was markedly increased in a mouse model carrying a WNK4 missense mutation (Q562E) previously identified in patients with PHAII. The upregulation of pendrin led to an increase in thiazide-sensitive sodium chloride absorption by the cortical collecting duct, and it caused metabolic acidosis. The function of apical potassium channels was altered in this model, and hyperkalemia was fully corrected by pendrin genetic ablation. Thus, we demonstrate an important contribution of pendrin in renal regulation of sodium chloride, potassium and acid-base homeostasis and in the pathophysiology of PHAII. Furthermore, we identify renal distal bicarbonate secretion as a novel mechanism of renal tubular acidosis.

Mutations in kelch-like 3 and cullin 3 cause hypertension and electrolyte abnormalities.

Hypertension affects one billion people and is a principal reversible risk factor for cardiovascular disease. Pseudohypoaldosteronism type II (PHAII), a rare Mendelian syndrome featuring hypertension, hyperkalaemia and metabolic acidosis, has revealed previously unrecognized physiology orchestrating the balance between renal salt reabsorption and K(+) and H(+) excretion. Here we used exome sequencing to identify mutations in kelch-like 3 (KLHL3) or cullin 3 (CUL3) in PHAII patients from 41 unrelated families. KLHL3 mutations are either recessive or dominant, whereas CUL3 mutations are dominant and predominantly de novo. CUL3 and BTB-domain-containing kelch proteins such as KLHL3 are components of cullin-RING E3 ligase complexes that ubiquitinate substrates bound to kelch propeller domains. Dominant KLHL3 mutations are clustered in short segments within the kelch propeller and BTB domains implicated in substrate and cullin binding, respectively. Diverse CUL3 mutations all result in skipping of exon 9, producing an in-frame deletion. Because dominant KLHL3 and CUL3 mutations both phenocopy recessive loss-of-function KLHL3 mutations, they may abrogate ubiquitination of KLHL3 substrates. Disease features are reversed by thiazide diuretics, which inhibit the Na-Cl cotransporter in the distal nephron of the kidney; KLHL3 and CUL3 are expressed in this location, suggesting a mechanistic link between KLHL3 and CUL3 mutations, increased Na-Cl reabsorption, and disease pathogenesis. These findings demonstrate the utility of exome sequencing in disease gene identification despite the combined complexities of locus heterogeneity, mixed models of transmission and frequent de novo mutation, and establish a fundamental role for KLHL3 and CUL3 in blood pressure, K(+) and pH homeostasis.

Hyperkalemia in young children: blood pressure checked?

Hyperkalemia in young children is a rare phenomenon and in many cases caused by hemolysis in the specimen due to difficulties in obtaining a sample. However, hyperkalemia can also be a sign of a rare Mendelian syndrome known as familial hyperkalemic hypertension or pseudohypoaldosteronism type II. This disease is characterized by hyperkalemia, hypertension, and mild hyperchloremic metabolic acidosis (with normal anion gap) despite normal glomerular filtration. Full recovery of these abnormalities with thiazide diuretics is essential not to miss the diagnosis of this syndrome. We describe two young patients with hyperkalemia as an incidental finding who were subsequently diagnosed with this rare endocrine disorder. Genetic testing revealed mutations in two recently discovered genes, the study of which has helped to unravel the pathophysiologic pathways. CONCLUSION: In patients with hyperkalemia and a normal glomerular filtration rate, the clinician should actively search for abnormalities in blood pressure since recognizing this condition can lead to simple, cheap, and effective treatment. What is Known: • True Hyperkalemia is rare in pediatrics and can be a sign of FHHt. What is New: • KLHL3 & CUL3 are recently discovered genes helping unravel the pathophysiologic pathway of FHHt.

Secondary pseudohypoaldosteronism causing cardiopulmonary arrest and cholelithiasis.

A 4-month-old boy presented with cardiopulmonary arrest on arrival after a brief period of lethargy. Laboratory examination indicated severe hyperkalemia, hyponatremia, metabolic acidosis, and slightly elevated C-reactive protein. Whole body computed tomography identified left-dominant hydronephrosis, hydroureter and cholelithiasis. Despite cardiac arrest >30 min, he was successfully resuscitated and treated with therapeutic hypothermia. Escherichia coli was detected on urine culture. Renal ultrasound showed bilateral hydronephrosis, grade II in the right and grade IV in the left. Retrospective analysis of the blood sample at admission indicated a high level of aldosterone. The patient recovered almost fully with no electrolyte imbalance and normal plasma renin and aldosterone, leading to the diagnosis of secondary pseudohypoaldosteronism associated with bilateral infected hydronephrosis. In this case, cholelithiasis, which may account for chronic dehydration, was a diagnostic clue in the absence of information of pre-existing situations.

Pseudohypoaldosteronism type-I: a rare cause of hyperkalemia in neonates.

Pseudohypoaldosteronism type I (PHA-I) is a rare disorder with only a few cases reported worldwide. It appears early in life with salt-wasting, failure to thrive, dehydration, hypotension, hyperkalaemia and metabolic acidosis. There is a resistance to aldosterone by the mineralocorticoid receptors. We describe one such case of a 14-day-old female neonate who presented with frequent episodes of dehydration, hyperkalaemia and hyponatraemia. On further workup, she proved to be a case of PHA-I. The aim of this report is to discuss the evaluation and to highlight the difficulties associated with the management of this rare disorder.

An unusual case of Pseudohypoaldosteronism coexisting with cystic fibrosis.

Pseudohypoaldosteronism type 1 is a rare congenital autosomal recessive disorder, characterised by failure of receptor response to aldosterone. It is caused by mutation in SCNN1A gene with clinical features like failure to thrive in infancy, hyponatraemia, hyperkalaemia and metabolic acidosis. We present a male infant with seizures, hyperkalaemia and with failure to thrive, diagnosed at day 6 of life. The baby required repeated correction for hyperkalaemia; hence, after ruling out treatable causes for hyperkalaemia, exonerated sequencing was done which showed pathogenic mutation for cystic fibrosis and recessive mutation for pseudohypoaldosteronism. But the child was clinically in favour of pseudohypoaldosteronism. Hence, features of pseudohypoaldosteronism predominate cystic fibrosis; they both may coexist.

Pseudohypoaldosteronism presenting with thrombocytosis and bilateral pneumothoraces in an infant.

Pseudohypoaldosteronism type 1 (PHA-1) is a rare salt-wasting syndrome caused by a peripheral resistance to aldosterone. Here, we describe an unusual presentation of the autosomal dominant PHA-1 featuring bilateral pneumothoraces at birth, thrombocytosis in infancy, and hypercalcemia in addition to the well-described findings of hyponatremia, hyperkalemia, and failure to thrive. These findings contribute to the limited case descriptions of PHA-1 and may suggest additional diagnostic considerations in a neonate presenting with hyperkalemia, hyponatremia, and failure to thrive.

Multilocus linkage of familial hyperkalaemia and hypertension, pseudohypoaldosteronism type II, to chromosomes 1q31-42 and 17p11-q21.

Essential hypertension is a common multifactorial trait. The molecular basis of a number of rare diseases that after blood pressure in humans has been established, identifying pathways that may be involved in more common forms of hypertension. Pseudohypoaldosteronism type II (PHAII, also known as familial hyperkalaemia and hypertension or Gordon's syndrome; OMIM #145260), is characterized by hyperkalaemia despite normal renal glomerular filtration, hypertension and correction of physiologic abnormalities by thiazide diuretics. Mild hyperchloremia, metabolic acidosis and suppressed plasma renin activity are variable associated findings. The pathogenesis of PHAII is unknown, although clinical studies indicate an abnormality in renal ion transport. As thiazide diuretics are among the most efficacious agents in the treatment of essential hypertension, understanding the pathogenesis of PHAII may be of relevance to more common forms of hypertension. Analysis of linkage in eight PHAII families showing autosomal dominant transmission demonstrates locus heterogeneity of this trait, with a multilocus lod score of 8.1 for linkage of PHAII to chromosomes 1q31-q42 and 17p11-q21. Interestingly, the chromosome-17 locus overlaps a syntenic interval in rat that contains a blood pressure quantitative trait locus (QTL). Our findings provide a first step toward identification of the molecular basis of PHAII.

Brugada syndrome uncovered in patient with pseudohypoaldosteronism due to hyperkalaemia.

Brugada syndrome is a rare sodium channelopathy that predisposes to an increased risk of malignant arrythmias and sudden cardiac death. Previous studies have reported that metabolic disturbances can uncover a Brugada ECG pattern. Given the risk of malignant arrhythmias, it is important to correctly diagnose and treat Brugada syndrome. We report a case of Brugada syndrome uncovered by hyperkalaemia precipitated in a patient with pseudohypoaldosteronism.

Miliaria rubra and thrombocytosis in pseudohypoaldosteronism: case report.

Pseudohypoaldosteronism type 1 (PHA1) is a disease involving a state of renal tubular unresponsiveness to the action of aldosterone and characterized by excessive salt loss in the urine, hyperkalemia, and metabolic acidosis. In kidney, PHA1 may occur primarily by mutations in the subunits of the sodium channel or in the mineralocorticoid receptors, and secondarily by several renal disorders. Miliaria rubra and thrombocytosis are reported in a 6-month-old girl with PHA1. In patients with PHA1, miliaria rubra-like cutaneous eruptions are suggested to occur due to obstruction of eccrine sweat glands through inflammation caused by excessive sodium excretion in sweat during hyponatremic crises. The presence of thrombocytosis in patients with PHA1 has not been previously reported. A hypothesis is proposed suggesting that sympathetic activation which provides vascular tonus during sodium excretion in sweat and salt-depletion crisis may play a role in the development of eruptions and thrombocytosis in patients with PHA1.

Neonatal renal venous thrombosis followed by secondary pseudohypoaldosteronism.

A male infant was diagnosed as having renal venous thrombosis (RVT) in association with bilateral flank masses, macroscopic hematuria, and thrombocytopenia. In the course of supportive treatment, hyponatremia, hyperkalemia, and metabolic acidosis became prominent. Plasma renin activity (PRA) and aldosterone increased markedly. Treatment with sufficient sodium chloride and sodium bicarbonate intake was effective. It is important to note that tubular damage by RVT causes secondary pseudohypoaldosteronism.

[Rapidly progressing quadriparesis secondary to licorice (souss) intoxication]. / Tétraparésie rapidement progressive par intoxication à la réglisse (souss).

INTRODUCTION: Regular consumption of licorice based beverages can provoke pseudohyperaldosteronism with hypokalemia but can rarely lead to severe muscle weakness. CASE REPORT: A 62-year-old man was admitted for a one-week history of progressive weakness of the four limbs. Blood work revealed severe hypokalemia that was due to primary pseudo-hyperaldosteronism secondary to licorice intoxication. He became normal after correction of the electrolytes disturbances. DISCUSSION & CONCLUSION: In an area where a liquorice-based beverage (souss), is frequently and sometimes excessively consumed, pseudo-hyperaldosteronism secondary to licorice toxicity should be thought of in front of any muscle weakness accompanied by hypokalemia. A rapid correction of electrolytes disturbances leads to rapid improvement.

Diagnostic and management considerations in pseudohypoaldosteronism type 1b.

Pseudohypoaldosteronism type 1B is a rare autosomal recessive disorder caused by dysfunction of amiloride-sensitive epithelial sodium channels (ENaCs). We present the case of a neonate with cardiogenic shock after cardiac arrest due to profound hyperkalaemia. Genetic testing revealed a novel homozygous variant in SCNNIA We review diagnostic considerations including the molecular mechanisms of disease, discuss treatment approaches and highlight the possible significance of the diversity of pulmonary ENaCs.